The present invention relates generally to automotive timing lights and more particularly to a timing light having stable brightness at high engine r.p.m.'s.
Many automotive timing lights presently available include a circuit containing a flash capacitor and a flash tube, connected for generating repetitive flashes of light in coordination with the firing of the number one cylinder of the engine. During operation of the timing light, the flash capacitor is charged to a particular voltage, often in a range between 500 and 700 volts, and then is discharged into the flash tube for generating the flash of light.
The charging of the flash capacitor takes a discrete period of time depending on the value of the flash capacitor and other charging circuit components which are involved. If the engine is running slowly, there is sufficient time after the flash capacitor has been discharged to re-charge the same to a full voltage prior to the next flash. In checking the vacuum and/or mechanical advance of the timing system of the engine, it becomes necessary to run the engine at high speeds. If the engine is running rapidly, however, insufficient time between successive firings of the number one cylinder will cause the flash capacitor not to fully charge. When this occurs, a smaller than normal amount of energy is stored in the flash capacitor and discharged through the flash tube. This will result in the generation of a weak flash of light or no flash at all.
Weak light flashes are undesirable since they make it difficult for an operator of the timing light to notice when the light flash occurs, particularly where the engine is being timed in a well-lit area.
If the flash capacitor has insufficient time to fully charge, the capacitor's voltage may prove insufficient to ionize the gas within the flash tube and no light flash will be emitted. This causes erratic flashing and subjects the timing light to criticism by consumers that the light is malfunctioning.